lasp/cpp_src/dsp/lasp_ppm.h

// lasp_ppm.h
//
// Author: J.A. de Jong - ASCEE
//
// Description: Peak Programme Meter
#pragma once
#include "lasp_filter.h"
#include "lasp_mathtypes.h"
#include "lasp_threadedindatahandler.h"

/**
 * \addtogroup dsp
 * @{
 *
 * \addtogroup rt 
 * @{
 */


/**
 * @brief Digital Peak Programme Meter (PPM). Let the latest maximum flow away
 * with a certain amount of dB/s. If a new peak is found, it goes up again.
 * Also detects clipping.
 * */
class PPMHandler : public ThreadedInDataHandler<PPMHandler> {

  /**
   * @brief Assuming full scale of a signal is +/- 1.0. If a value is found 
   */
  static inline const d clip_point = 0.98;

  /**
   * @brief How long it takes in [s] after a clip event has happened, that we
   * are actually still in 'clip' mode.
   */
  static inline const d clip_indication_time = 3.0;

  const d _decay_dBps;

  /**
   * @brief Inverse of block sampling frequency [s]: (framesPerBlock/fs) 
   */
  d _dt;

  /**
   * @brief 1st order low_pass value of levels, based on _decay_dBps;
   */
  d _alpha;

  mutable std::mutex _mtx;
  /**
   * @brief Current maximum values
   */
  vd _cur_max;

  /**
   * @brief How long ago the last clip has happened. Negative in case no clip
   * has happened.
   */
  vd _clip_time;

  /**
   * @brief Storage for maximum values
   */
  vd _max_range;

  public:
  /**
   * @brief Constructs Peak Programme Meter
   *
   * @param mgr Stream Mgr to install callbacks for
   * @param decay_dBps The level decay in units dB/s, after a peak has been
   * hit.
   */
  PPMHandler(SmgrHandle mgr,const d decay_dBps = 20.0);
  ~PPMHandler();

  /**
   * @brief Get the current values of the PPM. Returns an array of levels in dB
   * and a vector of True's. 
   *
   * @return Current levels in [dB], clipping indication
   */
  std::tuple<vd,arma::uvec> getCurrentValue() const;

  /**
   * @brief Implements callback on thread
   *
   * @param d DaqData to work with
   *
   * @return true when stream should continue.
   */
  void inCallback(const DaqData& d);
  void reset(const Daq*);

};

/** @} */
/** @} */